Polyunsaturated higher fatty acids such as arachidonic acid in the metabolism of mammals, including man, serve as substrates for the formation of physiologically important eicosanoids such as prostaglandins and leukotrienes (a group of compounds also known as "Slow Reacting Substance of Anaphylaxis" or "SRS-A") The pathway to prostaglandins is catalyzed by cyclo-oxygenase (also named "prostaglandin synthetase") whereas the pathway to leukotrienes is catalyzed by 5-lipoxygenase.
The prostaglandins are products of known beneficial functions in mammals while it is known for the leukotrienes or SRS-A, respectively, that they cause allergic reactions, bronchoconstrictions, inflammations, asthma and numerous other harmful effects Accordingly there is a need for chemically and metabolically stable agents which in the living organism have no effect on the biosynthesis of prostaglandins but inhibit selectively or specifically the activity of 5-lipoxygenase and thus prevent the formation of the undesired leukotrienes.